I'll offer an answer in two parts:
- A discussion of creation ex-nihilo
- The pre-mortal role of Jesus
--
Creation ex-nihilo
As noted in the OP, The Church of Jesus Christ of Latter-day Saints does not accept creation ex-nihilo. Members of the church hold that creation ex-nihilo is neither taught in the canonical scriptures (for Latter-day Saints that's the Bible, Book of Mormon, Doctrine & Covenants, and Pearl of Great Price), nor in the teachings of modern prophets (we believe God speaks through an authorized spokesperson today, just like He did through Moses or Isaiah--that's Joseph Smith and his successors up to the present-day President of the church, Russell M. Nelson).
One of the most direct discussions of creation ex-nihilo comes from Joseph Smith's King Follett discourse (I readily recognize that among many of my fellow Christians, this is considered to be among the least popular speeches ever given). I'm offering a Latter-day Saint perspective here, and Latter-day Saints consider Joseph Smith a prophet in every sense of the word that Moses was.
From the King Follett discourse:
You ask the learned doctors why they say the world was made out of
nothing, and they will answer, “Doesn’t the Bible say he created the
world?” And they infer, from the word create, that it must have been
made out of nothing. Now, the word create came from the word baurau,
which does not mean to create out of nothing; it means to organize;
the same as a man would organize materials and build a ship. Hence we
infer that God had materials to organize the world out of
chaos—chaotic matter, which is element, and in which dwells all the
glory. Element had an existence from the time He had. The pure
principles of element are principles which can never be destroyed;
they may be organized and re-organized, but not destroyed. They had no
beginning and can have no end.
Additional scriptural statements include:
Man was also in the beginning with God. Intelligence, or the light of
truth, was not created or made, neither indeed can be. (Doctrine &
Covenants 93:29)
The elements are eternal (Doctrine & Covenants 93:33)
Thus "create" is understood in the sense that the word is used in virtually all non-theological discussions--"create" means to organize. In the process, the creation is often imbued with attributes it did not previously have.
Blake Ostler has written extensively in defense of this view--here are 3 of his major arguments:
Most Latter-day Saints reject creation ex-nihilo because they have a personal testimony of the restoration of the gospel of Jesus Christ through the prophet Joseph Smith, and therefore conclude that God has given them reason to trust the doctrines taught by Joseph Smith (for a Biblical parallel, this is like saying most Christians believe the Gospel is intended for both Jews & Gentiles, because they believe what was recorded by Luke, Paul, etc.).
A few Latter-day Saints have additionally explored the history and the philosophy of creation ex-nihilo and reject it on those grounds as well.
Since this is a Christianity site, I'll refer the reader to the links above for the philosophy and focus here on what is taught in the Bible.
From Ostler:
There are three words in Hebrew scripture that can be translated in
English as create. [b_r_’, ‘asah, yatsar]...But a sharp distinction
between organizing preexisting material for ‘asah and absolute
creation where before there was nothing in any sense for b_r_’ is
simply an oversimplification. God made Israel out of preexisting
people [Isaiah 43:15] and a clean heart out of an existing heart
[Psalms 51:12]
On the other hand, these three verbs are often used interchangeably
and in parallel structures showing that they have essentially the same
semantic field. In Hebrew poetry, when words are placed in a parallel
form (parallelismus membrorum is the technical term) the words are
often used as synonyms or antonyms. For example, Isaiah 43:6-7 says:
Bring my sons from far,
and my daughters from the ends of the earth;
even every one that is called by my name:
for I have created (b_r_’ ) him for my glory,
I have formed (yatsar) him;
yea, I have made (‘asah) him.
Isaiah uses all three words for create to describe what God has done
for those called by his name. Moreover, none of these uses of the word
create in Hebrew mean to create ex nihilo, for they address how God
has taken an existing person and created a new personality in that
person to manifest his glory. Consider also Psalm 51:10 which uses the
verb b_r_’ : “Create (b_r_’ ) in me a clean heart, O God; and renew my
spirit within me.” In Psalm 33:15 the same thought is expressed using
the verb yatsar: “He fashioneth (yatsar) their hearts alike, he
considereth all their works.” The verbs b_r_’ and yatsar appear to be
used interchangeably or as synonyms.
...
[B]oth b_r_’ and ‘asah are used in parallel form in Isaiah 45:12 to
describe the creation of the earth and man: “I have made (‘asah) the
earth and created (b_r_’ ) man upon it.” In the same chapter of
Isaiah, God is said to create (yatsar ) the earth: “God himself that
formed (yatsar) the earth and made (‘asah) it; he created (b_r_’ ) it
not in vain, he formed (yatsar) it to be inhabited.” (Isaiah 45:7, 18)
It is abundantly clear from this verse that b_r_’ , yatsar and ‘asah
are used interchangeably, for God creates the earth in all three
senses.
...
However, the use of the verb b_r_’ does show that God accomplished a
marvelous act of creation with absolute ease by speaking and dividing
asunder preexisting realities. God makes by dividing asunder. He
created Israel by separating her from the existing nations in the same
way that he created the earth by dividing it from the primeval watery
chaos. In Hebrew thought, the cosmic world mirrors the social
structure of the Israelite nation. They were brought out of a state of
chaos and a desert waste to a sacred society ordered by God’s law and
covenant. However, there is always the threat of returning to this
chaos if Israel rejects God. Joseph Smith’s assertion that the verb
b_r_’ as used in Genesis 1:1 means that God organized a preexisting
chaos is actually quite plausible in context. (see section 3.1
here)
--
A brief discussion of Hebrews 11:3 as requested in the comments:
Another translation states: “It is by faith that we understand that
the ages were created by a word from God, so that from the invisible
the visible world came to be.” What this text says is that God created
visible things literally “from” invisible things (eis to me ek
fainomenon to blepomenon gegonenai). However, the invisible things are
not nothing; they already exist (section 4.0 here)
--
It is also worthwhile to trace the origins of creation ex-nihilo in Christian thought. One more quote from Ostler:
It is extremely significant that when the first “scriptural” arguments
in history were formulated to support the doctrine of creatio ex
nihilo by Irenaeus (about 185 A.D.) and Origen (220 A.D.) they do not
cite scriptures from the canon accepted by evangelicals and Mormons.
Rather, they cite The Shepherd of Hermas and 2 Maccabees 7:28. The
reason they cite these texts rather than other scriptures is obvious –
they did not know of any scriptures which supported the doctrine of
creation ex nihilo. It is ironic therefore that even these two texts
do not teach the dogma of creatio ex nihilo. It is also significant
that Hermas adopts the technical language for creation from relative
non-being ek tou me ontos which makes it fairly clear that God created
what is from potential being, not from absolute nothing or ex nihilo.
(see section 5.1 here)
--
The pre-mortal role of Jesus
The first Article of Faith of The Church of Jesus Christ of Latter-day Saints states:
We believe in God, the Eternal Father, and in His Son, Jesus Christ,
and in the Holy Ghost.
Latter-day Saints believe that they are 3 separate and distinct Beings, who are united in mission and purpose. Latter-day Saints understand God as a title, not a personal name, and definitively believe in the Deity of Jesus Christ. In the title page to the Book of Mormon the prophet Moroni summarized purposes of the book, including the statement:
to the convincing of the Jew and Gentile that Jesus is the
Christ, the Eternal God
The church's website offers a summary of its view of the Godhead here.
Latter-day Saints believe that the entire human family existed pre-mortally, and in the Deity of Christ prior to His birth. Specifically, Latter-day Saints believe that Jehovah is not the name of God the Father, but rather is the pre-mortal name of Jesus.
It was Jesus--Jehovah as He was known then--who as the perfect representative of His Father and a God in His own right, gave commandments to Moses. It was Jehovah who created the earth, under the direction of God the Father.
Isaiah 44:24:
Thus saith the Lord, thy redeemer, and he that formed thee from the
womb, I am the Lord that maketh all things; that stretcheth forth the
heavens alone; that spreadeth abroad the earth by myself;
In the Latter-day Saint view there is no conflict here. Jehovah (the Son of God the Father), who would later in mortality be known as Jesus of Nazareth, is speaking here. He is the Redeemer and the Creator.
Let's briefly disambiguate what is meant by father:
- The Father of our spirits (God the Father)
- The Father of creation (Jehovah/Jesus)
- The Father of our salvation (Jehovah/Jesus)
- The father of a human body (God the Father to Jesus, your Dad to you, me to my
children)
We believe in the Deity of Jehovah/Jesus, and that He is fully aligned with and obedient to the plan of God the Father, who is the Father of our spirits, the Father of Jesus' spirit, and the Father of Jesus' physical body.
It may be appropriate to say that God the Father is the architect who designed the universe and the plan of salvation, and the Jesus is the builder who made it a reality.
--
Conclusion
Latter-day Saints believe that Jehovah, who in mortality would be known as Jesus of Nazareth, created the world under the direction of His Father. We believe that "create" in both the Old & New Testaments (and the Book of Mormon if anyone is counting), describes not a creation out of nothing, but an organization of eternal elements.
Disclaimer (yes I'm including it again! =) ) - my comments are the product of my own study and do not constitute official statements by The Church of Jesus Christ of Latter-day Saints
Disclaimer 2 - I'm happy to dialogue with other users, but will offer a friendly reminder that argumentum ad hominem is a logical fallacy. Please be kind.